Diuretics Flashcards
Function of Kidney
- Regulation of water and electrolytes in body
- Retention of substances vital to the body
- Maintenance of acid-base reactions
Transcellular movement
Through apical and basolateral membranes
Paracellular movement
through space between tubular cells
What are diuretics
Drugs that increase excretion of sodium and chloride ions> increasing urine volume via action on the kidney. They act on a single zone in the kidney
What do diuretics treat
Oedema state, non-oedema state and hypertension
What are the classes of diuretics
- carbonic anhydrase inhibitor
- Osmotic diuretics
- Loop diuretics
- Thiazide diuretics
- Thiazide-like analogs
- ADH antagonists
What is oedema
Rate of fluid formation exceeds that of reabsorption. NaCl reabsorption too high> water retention
Treating oedematous states
- Cognitive heart failure: reduce ability to maintain cardaic output> increase blood volume
- Nephrotic syndrome: loss of prot reduces colloidal osmotic pressure
- Hepatic cirrhosis: Accumu of fluid in abdominal space
- Premenstrual oedema
Treating non-oedematous states
- hypertension: Reduce BV & dilate arteries
- Hypercalcaemia: Calcium excretion
- Diabetes insipidus: Reduce plasma vol, reduce GFR, increase reabsorption of water and sodium
Low ceiling diuretics
- Thiazide: rapid flattening dose effect curve. Not dose dependent
High ceiling diuretics
- Loop diuretics: dose dependent
Carbonic anhydrase inhibitor drug and their MOA
- Acetazolamide
- inhibits reabsorption of HCO3- in the proximal convoluted tubules
General MOA of carbonic anhydrase inhibitors
Inhibits exchange of across the sodium-hydrogen antiporter> inhibition sodium reabsorption> decrease ability to exchange Na+ for H+ in the presence of carbonic anhydrase> results in mild diuresis
Adverse effects of carbonic anhydrase inhibitors
- Acidosis
- Hypokalaemia
- Decreased uric acid secretion
Osmotic diuretic drugs and their MOA
- Mannitol, Glucose
- Increases osmolarity of tubular fluid, preventing water reabsorption> osmotic diuresis
- targets proximal tubule/ descending loop of Henle
Adverse effects of Osmotic diuretics
- Dehydration
- headache
Loop diuretic drugs and their MOA
- Furosemide, Bumetanide
- Inhibits cotransport of Na+/K+/2Cl-> decreasing reabsorption of these ions
- Greatest diuretic effect out of all diuretics
- targets ascending loop of Henle
Indications and adverse effects of loop diuretics
- acute pulmonary oedema, hypertension, hypercalcaemia
- Ototoxicity, hyperuricaemia, acute hypovolaemia
Thiazide diuretic drugs and their MOA
- Hydrochlorothiazide
- Inhibits reabsorption of Na+ and Cl- in the distal convoluted tubules> water retention in tubules and increased Na+ and Cl- conc in tubular fluid
- Also reduce peripheral vascular resistance
Indications and adverse effects of thiazide diuretics
- Hypertension, mild cognitive heart failure
- Orthostatic hypotension, erectile disfunction, hypokalaemia
Thiazide-like analog drugs and their MOA
- Chlothalidone, metaolzone, indapamide
- inhibit reabsorption of Na+ and Cl- in distal tubule> water retention ad increased conc of Na+ and Cl- in the tubular fluid
Aldosterone antagonistic drugs and their MOA
- Spiranolactone, amiloride, triamterene
- prevents translocation of the receptor complex into the nucleus of the target cell> failure in production of mediator proteins that normally stimulate the Na+/K+ exchange sites of collecting tubule> K+ and H+ secretion
Indication and adverse effects of aldosterone antagonists
- hypertension, heart failure
- hyperkalaemia, menstrual irregularities, decreases libido
ADH antagonistic drugs and their MOA
- Lithium, demeclocycline
- Decrease aquaporins in collecting ducts> decreasing water reabsorption in the collecting ducts
Indication of ADH antagonists
- SIADH
Natural diuretic herbs
- parsley
-holy basil - dandelion
Natural diuretic fruits and veg
- tomatoes
- cranberries
- asparagus
